Parents have been warned they face a "delicate balance" between supporting their child's sporting ambitions and pushing them too far.

In the worst cases, pushy parents risk damaging their child's mental or physical health, according to Rod Jaques, national medical director of the English Institute of Sport, which works with elite athletes.

He said he that in rare but "worrying" incidences a parents' love is "conditional" on the child achieving sporting success, which can lead to youngsters developing eating disorders or inventing injuries.

Addressing the Headmasters' and Headmistresses' Conference (HMC), Dr Jaques said: "I think it is a tough one when a parent comes into the consultation who is both the coach and parent. It is a potential for conflict of interest there.

"It's a very delicate balance between encouragement and support for that child, and its potential for being a mentor or a tormentor of the child I think is really quite real.

"It is often anecdotally said that behind every injured child is a parent athlete wanting to get out.

"Australians have gone a bit further and called this the ugly parent syndrome and we probably have witnessed this on the side of our rugby fields or football fields of the bawling parent, not just at the referee but at the child on the field of play.

"This love for their child should not be conditional on results and unfortunately it sometimes is."

The conference also heard that private school pupils are more likely to become Olympic athletes than their state school counterparts.

Dr Jaques told delegates that 34% of the Great Britain team at the Beijing games were educated privately, with almost half of Britain's medal haul won by privately educated athletes.